Apparatus for dehydrating gas



April 25, 1933. F. w. sPERR, JR

APPARATUS FOR DEHYDRATING GAS Original Filed Oct.

Patented Apr. 25, 1933 UNITED STATES FREDERICK .'W. SPEBR, JR., 01|' ,PITTSBURGH PENNSYLVANIA, ASSIGNOB T0 THE KOPIEIBS COMPANY 0F DELAWARE, A CORPORATION 0F DELAWARE 'rrm'rns Fon. nnnYnnaTINe eas riglnal application.A nled October l1, 1926, Serial No. 140,749. 'Divided and this application tiled December 30, 1930.

This application is a division of my application Serial No. 140,749, filed October 11, 1926, which ap lication has now matured into U. S. Patent o. 1,791,086, issued February 3,

My invention'relates to apparatus for dehydrating gas, such, for example, as fuel gases, coke oven gas, water gas and the like. An object of my invention is to provide s' ple and l eilicient means for reducmg the dew-point of gas. v

Another object of my invention is to pro4 vide against a rise .in temperature ofthe gas due to the heat of dilution of the hygroscopic agent. f

In accordance with my invention, I treat the gas lunder compression with a hygroscopicj agent, preferably either a concentrated solution of calcium chloride or sulphuric acid.

With respect to the use of the latter, a still further object of my invention is to avoid the dilution of the acid to such point that it could not be used to treat the gas for the recovery of ammonia and that it would becorrosi've with respect to the usual iron and steel apparatus employed, and also to balance the amount required for dehydrating the gas with the amount necessary for recovermg ammonia from the gas.

My invention has for further ojiects vsuch other new and useful operative vantages or' results as may herinaftei` be found to obthe single tain.

'In Aorder that jmy invention ma be clearly set forth and understood, the pre erredmanner 'in which it is embodied and performed willnow be described, with reference to the laccompanying drawing. In the drawing, ifgure is a diagrammatic view of apparatus or dehydratmo` means for compressing, cooling and treating Referring to the drawing, the gas to be deit is washed with cold water and reduced to a temperature as low as it is possible to' obtain in this manner. After leaving the tower 2, the gas passes upwardly through'a tower gas, including Y um fatina of @geheim dew me of 17mm and after Ca soluq -i compression tion "qn* mg mmm Femm; ma

Serial Nm 505,567.

3, which is provided with a plurality of contact means 4 and coolin means 5. During the passage of ythe gas rough the tower 3, 1t 1s was ed with a saturated solution of calcium chloride, whichv is' a hygroscopic agent capable of reducing the dew-point of the gas. By thus'compressing the gas and subsequently treating it while compressed, after cooling with a concentrated solution of clcium chloride, the dew-point of the treated Y gas, when allowed to expand to atmospheric pressure, will be considerabl lower than if the same gas, uncompresse were treated with the same solution at the same tem era-,

ture. It is known that calcium chlori e, as v `a hygros'copic agent, is most economically used Ain the form of a saturated solution.

However, using such a solution to treat gas,

. The actual pressures employed will vary according to thev dew-point desired in the treated gas and the degree of cooling possible with the available water for this purpose.

i The following table shows the pressure to which a Vgas must be compressed in order that the gas, after treatment with a concentrated calcium chloride solution and ex ansion to atmospheric pressure, will have a ewpoint of 30 F.

The actual equilibrium dew-point of the calcium chloride solution, as given above, isf-A taken as 6 F. above the theoretical, which has been found to be representative of practrcal results.

i 49 the gas. The excess volume o f the concenplayed, it will, of course, be realized that .With. regard to the actual pressures em` any fuel gas being treated will be under some pressure, and in certain systems, a, comparatively high distribution pressure may be necessary. The .economical pressures at which hood of one atmosp ere, more or less, de ending on circumstances. In anycase, i for example, lbs. pressure were required to squeeze out moisture from the gas to such point-that subsequent treatment with a'con- 'centrated solution of calcium .chloride would produce a dew-point suliciently low, for

example, F., this would not mean 15 lbs.,

A' gauge, but 15 lbs. above the distribution pressure. If the latter were 5 lbs.,'the actual gauge pressure during the treatment with the ygroscopic agent would be 20 lbs.

When calcium chloride solution is usedas the hygroscopic agent, the :solution will ordinarily be re-circulated, being reconcen- -trated .and cooled during re-circulation.

The solution leavingthe tower 3 passes by gravitv into a sump 6 and is forced by a pump l through a water-sprayed cooling coil` 8' and 'a spray system 9 into the tower 3. A

portion, or all, of the solution may be .passed through an evaporator 10, either continuoiisl or' intermittently for reconcentration.'

owever, an advantage of my invention resides in the fact that the amount of calcium chloride necessary may be reduced to such an economical ligure that 'reconcentration may be dispensed with. In this instance, the solution would be recirculated in the usual manfner, solid calcium chloride being added at any convenient point to account for the dilution caused by the moisture removed from trated' solution wouldthen be discarded, continuously or from time to time, and reconcentration would not be necessary.

It. will be seen that a supply of cooling water for f-.the tower 2, the coils 5 and the coils 8 is ordinarily required. This .water is allowed to accumulate in'a sump 11 situated below an atmospheric cooling tower 12. A portion ofthe water is pumped by a pump 13 through a spray system -14 over the tower 2 while a ortion is forced by a pump 15 through t e coils 5 and/or over the coils 8, as

. required. That portion of the water delivered by the pum 15- to the coils 5, together with the eiiluent rom the tower 2, drains into a sump 16, while that portion which has passed over the coils 8 collects in a sump 17. umps 18 and 19 force the water from sumps 16 and 17, respectively, over the atmos heric cooling tower 12wliere water is coo ed as much as possible, according to the temperature of the atmosphere before descending mtothesumpll.' i'

The comtgress'ed, cooled and treated gas I iows from e tower 3 into a pressure Storage I prefer to oplerate are in the neighborpending upo conditions and with m tank`20gand is released through a regulator. 21 at normal pressure into a storage holder 22, or the mains.

When sulphuric acid is used as the h groscopic agent, it maybe reconcentrate and recirculated, but this is more difficult than is the case w'hen a salt solutionv is employed.

Furthermore, as sulphuric. acid is ordinarily used to treat the gas for the removal of ammonia as ammonium sulphate, itis preferable to pass concentrated acid through the treating tower but once and to so regulate the dilution of the acid that the diluted acid may be employed in the saturator and is still so concentrated as to avoid corrosion of the iron and steel apparatus' which it is most convenient to employ. i

In this case, concentrated sulphuric acid of, f or example, Baume` strength, is supplied to the tower 3 from a tank 23. After traversing the tower 3 in contact with the gas, the diluted acid drains into the sump 6 and is supplied tothe saturators.

lIn prior practice using sulphuric acid of 609 Baume strength, the reduction of colte- .oven gas saturated at 80 F. to a dew-point of 30 F. would require 62.3 pounds of 60 Baume acid per tonof coal carbonized,v provided the dilution of the acid is not carried below. 50 Baum. This amount of sulphuric acid is considerably in excess of the normal vrequirement -for ammonium sulphate,v recovery, which is 25 pounds of 60 Baume per ton of coal carbonized.v l

In thev copending application of Charles J. Ramsburg, Serial No. 45,674, filed July 2% 1925, a system lof dehydration is describe -and claimed in which the dehydration of gas is accomplished by means of sulphuric acid,

the amount necessary for recovering am-` monia from the total s. Under modern ern coke ovens, there is a growing and already well-established tendency to use producer gas or other cheap gas for underringthe ovens, thusgreleasing all of the valuable coke-oven for distribution. In this case, the dehy rationof the total gas,'even with Ramsburgs improved methods, would produce dilute acid :.However, according to my invention, the

amount considerably above-the sulphate requirement.

amount of acid required for dehydration of the total gas can be reduced to ther-ammonium sulphate requirement or even less, if so desired, by varying the pressure to which the gas is compressed and the temperature to which it is cooled after compression.

My invention makes possible the dehydration of gas to a dew-point lower than heretofore possible with hygroscopic agents of the nature indicated and without refrigeration.

My invention is `not limited to the specific example 'given hereinabove by Way of illustration but may variously be employed with- .in the scope of the following claim. I claim as my invention: Apparatus for dehydrating fuel'gas which comprises, in combination, a compressor located in the path of the gas, a direct cooler and' a scrubber having internally disposed direct-contact sections and indirect` cooling sections, located in the path of the compressed gas, a brine cooler,vmeans for recirculating a water absorbent brine through said `brine-cooler and the direct-contact sections of said scrubber, an atmospheric cool-l ing tower, and means for supplying cooled water from said tower to said direct cooler, the indirect cooling sections of said scrubber and said brine-cooler." In testimony whereof, I have hereunto subscribed my name this 19th day of December 1930. e 35 FREDERICK W. SPERR, JR. f 

